<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>c3 calc函数运用</title>
    <style>
        .fhter {
           
            margin: 100px auto;
            width: 200px;
            height: 200px;
            background-color: pink;
           
        }
       .fhter .son {
           
        
        height: 100px;

           background-color: skyblue;
           /* 这里注意calc是运算函数 括号里的运算符号 + - * \ 左右两边各有一个空格 否则无效 */
           width: calc(100% - 30px);
       }
       
    </style>
</head>
<body>
    <div class="fhter">
        <div class="son"></div>
    </div>
</body>
</html>